all messages for Emacs-related lists mirrored at yhetil.org
 help / color / mirror / code / Atom feed
blob 617f6ae5e8013ae3e5b310d663dd3dd11364826c 79664 bytes (raw)
name: lisp/help-fns.el 	 # note: path name is non-authoritative(*)

   1
   2
   3
   4
   5
   6
   7
   8
   9
  10
  11
  12
  13
  14
  15
  16
  17
  18
  19
  20
  21
  22
  23
  24
  25
  26
  27
  28
  29
  30
  31
  32
  33
  34
  35
  36
  37
  38
  39
  40
  41
  42
  43
  44
  45
  46
  47
  48
  49
  50
  51
  52
  53
  54
  55
  56
  57
  58
  59
  60
  61
  62
  63
  64
  65
  66
  67
  68
  69
  70
  71
  72
  73
  74
  75
  76
  77
  78
  79
  80
  81
  82
  83
  84
  85
  86
  87
  88
  89
  90
  91
  92
  93
  94
  95
  96
  97
  98
  99
 100
 101
 102
 103
 104
 105
 106
 107
 108
 109
 110
 111
 112
 113
 114
 115
 116
 117
 118
 119
 120
 121
 122
 123
 124
 125
 126
 127
 128
 129
 130
 131
 132
 133
 134
 135
 136
 137
 138
 139
 140
 141
 142
 143
 144
 145
 146
 147
 148
 149
 150
 151
 152
 153
 154
 155
 156
 157
 158
 159
 160
 161
 162
 163
 164
 165
 166
 167
 168
 169
 170
 171
 172
 173
 174
 175
 176
 177
 178
 179
 180
 181
 182
 183
 184
 185
 186
 187
 188
 189
 190
 191
 192
 193
 194
 195
 196
 197
 198
 199
 200
 201
 202
 203
 204
 205
 206
 207
 208
 209
 210
 211
 212
 213
 214
 215
 216
 217
 218
 219
 220
 221
 222
 223
 224
 225
 226
 227
 228
 229
 230
 231
 232
 233
 234
 235
 236
 237
 238
 239
 240
 241
 242
 243
 244
 245
 246
 247
 248
 249
 250
 251
 252
 253
 254
 255
 256
 257
 258
 259
 260
 261
 262
 263
 264
 265
 266
 267
 268
 269
 270
 271
 272
 273
 274
 275
 276
 277
 278
 279
 280
 281
 282
 283
 284
 285
 286
 287
 288
 289
 290
 291
 292
 293
 294
 295
 296
 297
 298
 299
 300
 301
 302
 303
 304
 305
 306
 307
 308
 309
 310
 311
 312
 313
 314
 315
 316
 317
 318
 319
 320
 321
 322
 323
 324
 325
 326
 327
 328
 329
 330
 331
 332
 333
 334
 335
 336
 337
 338
 339
 340
 341
 342
 343
 344
 345
 346
 347
 348
 349
 350
 351
 352
 353
 354
 355
 356
 357
 358
 359
 360
 361
 362
 363
 364
 365
 366
 367
 368
 369
 370
 371
 372
 373
 374
 375
 376
 377
 378
 379
 380
 381
 382
 383
 384
 385
 386
 387
 388
 389
 390
 391
 392
 393
 394
 395
 396
 397
 398
 399
 400
 401
 402
 403
 404
 405
 406
 407
 408
 409
 410
 411
 412
 413
 414
 415
 416
 417
 418
 419
 420
 421
 422
 423
 424
 425
 426
 427
 428
 429
 430
 431
 432
 433
 434
 435
 436
 437
 438
 439
 440
 441
 442
 443
 444
 445
 446
 447
 448
 449
 450
 451
 452
 453
 454
 455
 456
 457
 458
 459
 460
 461
 462
 463
 464
 465
 466
 467
 468
 469
 470
 471
 472
 473
 474
 475
 476
 477
 478
 479
 480
 481
 482
 483
 484
 485
 486
 487
 488
 489
 490
 491
 492
 493
 494
 495
 496
 497
 498
 499
 500
 501
 502
 503
 504
 505
 506
 507
 508
 509
 510
 511
 512
 513
 514
 515
 516
 517
 518
 519
 520
 521
 522
 523
 524
 525
 526
 527
 528
 529
 530
 531
 532
 533
 534
 535
 536
 537
 538
 539
 540
 541
 542
 543
 544
 545
 546
 547
 548
 549
 550
 551
 552
 553
 554
 555
 556
 557
 558
 559
 560
 561
 562
 563
 564
 565
 566
 567
 568
 569
 570
 571
 572
 573
 574
 575
 576
 577
 578
 579
 580
 581
 582
 583
 584
 585
 586
 587
 588
 589
 590
 591
 592
 593
 594
 595
 596
 597
 598
 599
 600
 601
 602
 603
 604
 605
 606
 607
 608
 609
 610
 611
 612
 613
 614
 615
 616
 617
 618
 619
 620
 621
 622
 623
 624
 625
 626
 627
 628
 629
 630
 631
 632
 633
 634
 635
 636
 637
 638
 639
 640
 641
 642
 643
 644
 645
 646
 647
 648
 649
 650
 651
 652
 653
 654
 655
 656
 657
 658
 659
 660
 661
 662
 663
 664
 665
 666
 667
 668
 669
 670
 671
 672
 673
 674
 675
 676
 677
 678
 679
 680
 681
 682
 683
 684
 685
 686
 687
 688
 689
 690
 691
 692
 693
 694
 695
 696
 697
 698
 699
 700
 701
 702
 703
 704
 705
 706
 707
 708
 709
 710
 711
 712
 713
 714
 715
 716
 717
 718
 719
 720
 721
 722
 723
 724
 725
 726
 727
 728
 729
 730
 731
 732
 733
 734
 735
 736
 737
 738
 739
 740
 741
 742
 743
 744
 745
 746
 747
 748
 749
 750
 751
 752
 753
 754
 755
 756
 757
 758
 759
 760
 761
 762
 763
 764
 765
 766
 767
 768
 769
 770
 771
 772
 773
 774
 775
 776
 777
 778
 779
 780
 781
 782
 783
 784
 785
 786
 787
 788
 789
 790
 791
 792
 793
 794
 795
 796
 797
 798
 799
 800
 801
 802
 803
 804
 805
 806
 807
 808
 809
 810
 811
 812
 813
 814
 815
 816
 817
 818
 819
 820
 821
 822
 823
 824
 825
 826
 827
 828
 829
 830
 831
 832
 833
 834
 835
 836
 837
 838
 839
 840
 841
 842
 843
 844
 845
 846
 847
 848
 849
 850
 851
 852
 853
 854
 855
 856
 857
 858
 859
 860
 861
 862
 863
 864
 865
 866
 867
 868
 869
 870
 871
 872
 873
 874
 875
 876
 877
 878
 879
 880
 881
 882
 883
 884
 885
 886
 887
 888
 889
 890
 891
 892
 893
 894
 895
 896
 897
 898
 899
 900
 901
 902
 903
 904
 905
 906
 907
 908
 909
 910
 911
 912
 913
 914
 915
 916
 917
 918
 919
 920
 921
 922
 923
 924
 925
 926
 927
 928
 929
 930
 931
 932
 933
 934
 935
 936
 937
 938
 939
 940
 941
 942
 943
 944
 945
 946
 947
 948
 949
 950
 951
 952
 953
 954
 955
 956
 957
 958
 959
 960
 961
 962
 963
 964
 965
 966
 967
 968
 969
 970
 971
 972
 973
 974
 975
 976
 977
 978
 979
 980
 981
 982
 983
 984
 985
 986
 987
 988
 989
 990
 991
 992
 993
 994
 995
 996
 997
 998
 999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
1766
1767
1768
1769
1770
1771
1772
1773
1774
1775
1776
1777
1778
1779
1780
1781
1782
1783
1784
1785
1786
1787
1788
1789
1790
1791
1792
1793
1794
1795
1796
1797
1798
1799
1800
1801
1802
1803
1804
1805
1806
1807
1808
1809
1810
1811
1812
1813
1814
1815
1816
1817
1818
1819
1820
1821
1822
1823
1824
1825
1826
1827
1828
1829
1830
1831
1832
1833
1834
1835
1836
1837
1838
1839
1840
1841
1842
1843
1844
1845
1846
1847
1848
1849
1850
1851
1852
1853
1854
1855
1856
1857
1858
1859
1860
1861
1862
1863
1864
1865
1866
1867
1868
1869
1870
1871
1872
1873
1874
1875
1876
1877
1878
1879
1880
1881
1882
1883
1884
1885
1886
1887
1888
1889
1890
1891
1892
1893
1894
1895
1896
1897
1898
1899
1900
1901
1902
1903
1904
1905
1906
1907
1908
1909
1910
1911
1912
1913
1914
1915
1916
1917
1918
1919
1920
1921
 
;;; help-fns.el --- Complex help functions -*- lexical-binding: t -*-

;; Copyright (C) 1985-1986, 1993-1994, 1998-2020 Free Software
;; Foundation, Inc.

;; Maintainer: emacs-devel@gnu.org
;; Keywords: help, internal
;; Package: emacs

;; This file is part of GNU Emacs.

;; GNU Emacs is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.

;; GNU Emacs is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.

;; You should have received a copy of the GNU General Public License
;; along with GNU Emacs.  If not, see <https://www.gnu.org/licenses/>.

;;; Commentary:

;; This file contains those help commands which are complicated, and
;; which may not be used in every session.  For example
;; `describe-function' will probably be heavily used when doing elisp
;; programming, but not if just editing C files.  Simpler help commands
;; are in help.el

;;; Code:

(require 'cl-lib)
(require 'help-mode)
(require 'radix-tree)
(eval-when-compile (require 'subr-x))   ;For when-let.

(defvar help-fns-describe-function-functions nil
  "List of functions to run in help buffer in `describe-function'.
Those functions will be run after the header line and argument
list was inserted, and before the documentation will be inserted.
The functions will receive the function name as argument.
They can assume that a newline was output just before they were called,
and they should terminate any of their own output with a newline.
By convention they should indent their output by 2 spaces.")

(defvar help-fns-describe-variable-functions nil
  "List of functions to run in help buffer in `describe-variable'.
Those functions will be run after the header line and value was inserted,
and before the documentation will be inserted.
The functions will receive the variable name as argument.
They can assume that a newline was output just before they were called,
and they should terminate any of their own output with a newline.
By convention they should indent their output by 2 spaces.
Current buffer is the buffer in which we queried the variable,
and the output should go to `standard-output'.")

(defvar help-fns-describe-face-functions nil
  "List of functions to run in help buffer in `describe-face'.
The functions will be used (and take the same parameters) as
described in `help-fns-describe-variable-functions', except that
the functions are called with two parameters: The face and the
frame.")

;; Functions

(defvar help-definition-prefixes nil
  ;; FIXME: We keep `definition-prefixes' as a hash-table so as to
  ;; avoid pre-loading radix-tree and because it takes slightly less
  ;; memory.  But when we use this table it's more efficient to
  ;; represent it as a radix tree, since the main operation is to do
  ;; `radix-tree-prefixes'.  Maybe we should just bite the bullet and
  ;; use a radix tree for `definition-prefixes' (it's not *that*
  ;; costly, really).
  "Radix-tree representation replacing `definition-prefixes'.")

(defun help-definition-prefixes ()
  "Return the up-to-date radix-tree form of `definition-prefixes'."
  (when (> (hash-table-count definition-prefixes) 0)
    (maphash (lambda (prefix files)
               (let ((old (radix-tree-lookup help-definition-prefixes prefix)))
                 (setq help-definition-prefixes
                       (radix-tree-insert help-definition-prefixes
                                          prefix (append old files)))))
             definition-prefixes)
    (clrhash definition-prefixes))
  help-definition-prefixes)

(defun help--loaded-p (file)
  "Try and figure out if FILE has already been loaded."
  ;; FIXME: this regexp business is not good enough: for file
  ;; `toto', it will say `toto' is loaded when in reality it was
  ;; just cedet/semantic/toto that has been loaded.
  (or (let ((feature (intern-soft file)))
        (and feature (featurep feature)))
      (let* ((re (load-history-regexp file))
             (done nil))
        (dolist (x load-history)
          (and (stringp (car x)) (string-match-p re (car x)) (setq done t)))
        done)))

(defun help--load-prefixes (prefixes)
  (pcase-dolist (`(,prefix . ,files) prefixes)
    (setq help-definition-prefixes
          (radix-tree-insert help-definition-prefixes prefix nil))
    (dolist (file files)
      ;; FIXME: Should we scan help-definition-prefixes to remove
      ;; other prefixes of the same file?
      (unless (help--loaded-p file)
        (with-demoted-errors "while loading: %S"
          (load file 'noerror 'nomessage))))))


(define-obsolete-variable-alias 'help-enable-completion-auto-load
  'help-enable-completion-autoload "27.1")

(defcustom help-enable-completion-autoload t
  "Whether completion for Help commands can perform autoloading.
If non-nil, whenever invoking completion for `describe-function'
or `describe-variable' load files that might contain definitions
with the current prefix.  The files are chosen according to
`definition-prefixes'."
  :type 'boolean
  :group 'help
  :version "26.3")

(defun help--symbol-completion-table (string pred action)
  (when help-enable-completion-autoload
    (let ((prefixes (radix-tree-prefixes (help-definition-prefixes) string)))
      (help--load-prefixes prefixes)))
  (let ((prefix-completions
         (and help-enable-completion-autoload
              (mapcar #'intern (all-completions string definition-prefixes)))))
    (complete-with-action action obarray string
                          (if pred (lambda (sym)
                                     (or (funcall pred sym)
                                         (memq sym prefix-completions)))))))

(defvar describe-function-orig-buffer nil
  "Buffer that was current when `describe-function' was invoked.
Functions on `help-fns-describe-function-functions' can use this
to get buffer-local values.")

;;;###autoload
(defun describe-function (function)
  "Display the full documentation of FUNCTION (a symbol).
When called from lisp, FUNCTION may also be a function object."
  (interactive
   (let* ((fn (function-called-at-point))
          (enable-recursive-minibuffers t)
          (val (completing-read
                (format-prompt "Describe function" fn)
                #'help--symbol-completion-table
                (lambda (f) (or (fboundp f) (get f 'function-documentation)))
                t nil nil
                (and fn (symbol-name fn)))))
     (unless (equal val "")
       (setq fn (intern val)))
     (unless (and fn (symbolp fn))
       (user-error "You didn't specify a function symbol"))
     (unless (or (fboundp fn) (get fn 'function-documentation))
       (user-error "Symbol's function definition is void: %s" fn))
     (list fn)))

  ;; We save describe-function-orig-buffer on the help xref stack, so
  ;; it is restored by the back/forward buttons.  'help-buffer'
  ;; expects (current-buffer) to be a help buffer when processing
  ;; those buttons, so we can't change the current buffer before
  ;; calling that.
  (let ((describe-function-orig-buffer
         (or describe-function-orig-buffer
             (current-buffer))))

    (help-setup-xref
     (list (lambda (function buffer)
             (let ((describe-function-orig-buffer
                    (if (buffer-live-p buffer) buffer)))
               (describe-function function)))
           function describe-function-orig-buffer)
     (called-interactively-p 'interactive))

    (save-excursion
      (with-help-window (help-buffer)
        (if (get function 'reader-construct)
            (princ function)
          (prin1 function))
        ;; Use " is " instead of a colon so that
        ;; it is easier to get out the function name using forward-sexp.
        (princ " is ")
        (describe-function-1 function)
        (with-current-buffer standard-output
          ;; Return the text we displayed.
          (buffer-string))))
    ))


;; Could be this, if we make symbol-file do the work below.
;; (defun help-C-file-name (subr-or-var kind)
;;   "Return the name of the C file where SUBR-OR-VAR is defined.
;; KIND should be `var' for a variable or `subr' for a subroutine."
;;   (symbol-file (if (symbolp subr-or-var) subr-or-var
;; 		 (subr-name subr-or-var))
;; 	       (if (eq kind 'var) 'defvar 'defun)))
;;;###autoload
(defun help-C-file-name (subr-or-var kind)
  "Return the name of the C file where SUBR-OR-VAR is defined.
KIND should be `var' for a variable or `subr' for a subroutine.
If we can't find the file name, nil is returned."
  (let ((docbuf (get-buffer-create " *DOC*"))
	(name (if (eq 'var kind)
		  (concat "V" (symbol-name subr-or-var))
		(concat "F" (subr-name (advice--cd*r subr-or-var))))))
    (with-current-buffer docbuf
      (goto-char (point-min))
      (if (eobp)
	  (insert-file-contents-literally
	   (expand-file-name internal-doc-file-name doc-directory)))
      (let ((file (catch 'loop
		    (while t
		      (let ((pnt (search-forward (concat "\^_" name "\n")
                                                 nil t)))
                        (if (not pnt)
                            (throw 'loop nil)
			  (re-search-backward "\^_S\\(.*\\)")
			  (let ((file (match-string 1)))
			    (if (member file build-files)
			        (throw 'loop file)
			      (goto-char pnt)))))))))
        (if (not file)
            nil
	  (if (string-match "^ns.*\\(\\.o\\|obj\\)\\'" file)
	      (setq file (replace-match ".m" t t file 1))
	    (if (string-match "\\.\\(o\\|obj\\)\\'" file)
	        (setq file (replace-match ".c" t t file))))
	  (if (string-match "\\.\\(c\\|m\\)\\'" file)
	      (concat "src/" file)
	    file))))))

(defcustom help-downcase-arguments nil
  "If non-nil, argument names in *Help* buffers are downcased."
  :type 'boolean
  :group 'help
  :version "23.2")

(defun help-highlight-arg (arg)
  "Highlight ARG as an argument name for a *Help* buffer.
Return ARG in face `help-argument-name'; ARG is also downcased
if the variable `help-downcase-arguments' is non-nil."
  (propertize (if help-downcase-arguments (downcase arg) arg)
	      'face 'help-argument-name))

(defun help-do-arg-highlight (doc args)
  (with-syntax-table (make-syntax-table emacs-lisp-mode-syntax-table)
    (modify-syntax-entry ?\- "w")
    (dolist (arg args)
      (setq doc (replace-regexp-in-string
                 ;; This is heuristic, but covers all common cases
                 ;; except ARG1-ARG2
                 (concat "\\<"                   ; beginning of word
                         "\\(?:[a-z-]*-\\)?"     ; for xxx-ARG
                         "\\("
                         (regexp-quote arg)
                         "\\)"
                         "\\(?:es\\|s\\|th\\)?"  ; for ARGth, ARGs
                         "\\(?:-[a-z0-9-]+\\)?"  ; for ARG-xxx, ARG-n
                         "\\(?:-[{([<`\"‘].*?\\)?"; for ARG-{x}, (x), <x>, [x], `x', ‘x’
                         "\\>")                  ; end of word
                 (help-highlight-arg arg)
                 doc t t 1)))
    doc))

(defun help-highlight-arguments (usage doc &rest args)
  (when (and usage (string-match "^(" usage))
    (with-temp-buffer
      (insert usage)
      (goto-char (point-min))
      (let ((case-fold-search nil)
            (next (not (or args (looking-at "\\["))))
            (opt nil))
        ;; Make a list of all arguments
        (skip-chars-forward "^ ")
        (while next
          (or opt (not (looking-at " &")) (setq opt t))
          (if (not (re-search-forward " \\([\\[(]*\\)\\([^] &).]+\\)" nil t))
              (setq next nil)
            (setq args (cons (match-string 2) args))
            (when (and opt (string= (match-string 1) "("))
              ;; A pesky CL-style optional argument with default value,
              ;; so let's skip over it
              (search-backward "(")
              (goto-char (scan-sexps (point) 1)))))
        ;; Highlight arguments in the USAGE string
        (setq usage (help-do-arg-highlight (buffer-string) args))
        ;; Highlight arguments in the DOC string
        (setq doc (and doc (help-do-arg-highlight doc args))))))
  ;; Return value is like the one from help-split-fundoc, but highlighted
  (cons usage doc))

;; The following function was compiled from the former functions
;; `describe-simplify-lib-file-name' and `find-source-lisp-file' with
;; some excerpts from `describe-function-1' and `describe-variable'.
;; The only additional twists provided are (1) locate the defining file
;; for autoloaded functions, and (2) give preference to files in the
;; "install directory" (directories found via `load-path') rather than
;; to files in the "compile directory" (directories found by searching
;; the loaddefs.el file).  We autoload it because it's also used by
;; `describe-face' (instead of `describe-simplify-lib-file-name').

;;;###autoload
(defun find-lisp-object-file-name (object type)
  "Guess the file that defined the Lisp object OBJECT, of type TYPE.
OBJECT should be a symbol associated with a function, variable, or face;
  alternatively, it can be a function definition.
If TYPE is `defvar', search for a variable definition.
If TYPE is `defface', search for a face definition.
If TYPE is not a symbol, search for a function definition.

The return value is the absolute name of a readable file where OBJECT is
defined.  If several such files exist, preference is given to a file
found via `load-path'.  The return value can also be `C-source', which
means that OBJECT is a function or variable defined in C.  If no
suitable file is found, return nil."
  (let* ((autoloaded (autoloadp type))
	 (file-name (or (and autoloaded (nth 1 type))
			(symbol-file
                         ;; FIXME: Why do we have this weird "If TYPE is the
                         ;; value returned by `symbol-function' for a function
                         ;; symbol" exception?
			 object (or (if (symbolp type) type) 'defun)))))
    (cond
     (autoloaded
      ;; An autoloaded function: Locate the file since `symbol-function'
      ;; has only returned a bare string here.
      (setq file-name
	    (locate-file file-name load-path '(".el" ".elc") 'readable)))
     ((and (stringp file-name)
	   (string-match "[.]*loaddefs.el\\'" file-name))
      ;; An autoloaded variable or face.  Visit loaddefs.el in a buffer
      ;; and try to extract the defining file.  The following form is
      ;; from `describe-function-1' and `describe-variable'.
      (let ((location
	     (condition-case nil
		 (find-function-search-for-symbol object nil file-name)
	       (error nil))))
	(when (cdr location)
	  (with-current-buffer (car location)
	    (goto-char (cdr location))
	    (when (re-search-backward
		   "^;;; Generated autoloads from \\(.*\\)" nil t)
	      (setq file-name
		    (locate-file
		     (file-name-sans-extension
		      (match-string-no-properties 1))
		     load-path '(".el" ".elc") 'readable))))))))

    (cond
     ((and (not file-name) (subrp type))
      ;; A built-in function.  The form is from `describe-function-1'.
      (if (get-buffer " *DOC*")
	  (help-C-file-name type 'subr)
	'C-source))
     ((and (not file-name) (symbolp object)
           (eq type 'defvar)
	   (integerp (get object 'variable-documentation)))
      ;; A variable defined in C.  The form is from `describe-variable'.
      (if (get-buffer " *DOC*")
	  (help-C-file-name object 'var)
	'C-source))
     ((not (stringp file-name))
      ;; If we don't have a file-name string by now, we lost.
      nil)
     ;; Now, `file-name' should have become an absolute file name.
     ;; For files loaded from ~/.foo.elc, try ~/.foo.
     ;; This applies to config files like ~/.emacs,
     ;; which people sometimes compile.
     ((let (fn)
	(and (string-match "\\`\\..*\\.elc\\'"
			   (file-name-nondirectory file-name))
	     (string-equal (file-name-directory file-name)
			   (file-name-as-directory (expand-file-name "~")))
	     (file-readable-p (setq fn (file-name-sans-extension file-name)))
	     fn)))
     ;; When the Elisp source file can be found in the install
     ;; directory, return the name of that file.
     ((let ((lib-name
	     (if (string-match "[.]elc\\'" file-name)
		 (substring-no-properties file-name 0 -1)
	       file-name)))
	(or (and (file-readable-p lib-name) lib-name)
	    ;; The library might be compressed.
	    (and (file-readable-p (concat lib-name ".gz")) lib-name))))
     ((let* ((lib-name (file-name-nondirectory file-name))
	     ;; The next form is from `describe-simplify-lib-file-name'.
	     (file-name
	      ;; Try converting the absolute file name to a library
	      ;; name, convert that back to a file name and see if we
	      ;; get the original one.  If so, they are equivalent.
	      (if (equal file-name (locate-file lib-name load-path '("")))
		  (if (string-match "[.]elc\\'" lib-name)
		      (substring-no-properties lib-name 0 -1)
		    lib-name)
		file-name))
	     (src-file (locate-library file-name t nil 'readable)))
	(and src-file (file-readable-p src-file) src-file))))))

(defun help-fns--key-bindings (function)
  (when (commandp function)
    (let ((pt2 (with-current-buffer standard-output (point)))
          (remapped (command-remapping function)))
      (unless (memq remapped '(ignore undefined))
        (let ((keys (where-is-internal
                     (or remapped function) overriding-local-map nil nil))
              non-modified-keys)
          (if (and (eq function 'self-insert-command)
                   (vectorp (car-safe keys))
                   (consp (aref (car keys) 0)))
              (princ "It is bound to many ordinary text characters.\n")
            ;; Which non-control non-meta keys run this command?
            (dolist (key keys)
              (if (member (event-modifiers (aref key 0)) '(nil (shift)))
                  (push key non-modified-keys)))
            (when remapped
              (princ "Its keys are remapped to ")
              (princ (if (symbolp remapped)
                         (format-message "`%s'" remapped)
		       "an anonymous command"))
              (princ ".\n"))

            (when keys
              (princ (if remapped
                         "Without this remapping, it would be bound to "
                       "It is bound to "))
              ;; If lots of ordinary text characters run this command,
              ;; don't mention them one by one.
              (if (< (length non-modified-keys) 10)
                  (princ (mapconcat #'key-description keys ", "))
                (dolist (key non-modified-keys)
                  (setq keys (delq key keys)))
                (if keys
                    (progn
                      (princ (mapconcat #'key-description keys ", "))
                      (princ ", and many ordinary text characters"))
                  (princ "many ordinary text characters"))))
            (when (or remapped keys non-modified-keys)
              (princ ".")
              (terpri)))))

      (with-current-buffer standard-output
        (fill-region-as-paragraph pt2 (point))
        (unless (looking-back "\n\n" (- (point) 2))
          (terpri))))))

(defun help-fns--compiler-macro (function)
  (let ((handler (function-get function 'compiler-macro)))
    (when handler
      (insert "  This function has a compiler macro")
      (if (symbolp handler)
          (progn
            (insert (format-message " `%s'" handler))
            (save-excursion
              (re-search-backward (substitute-command-keys "`\\([^`']+\\)'")
                                  nil t)
              (help-xref-button 1 'help-function handler)))
        ;; FIXME: Obsolete since 24.4.
        (let ((lib (get function 'compiler-macro-file)))
          (when (stringp lib)
            (insert (format-message " in `%s'" lib))
            (save-excursion
              (re-search-backward (substitute-command-keys "`\\([^`']+\\)'")
                                  nil t)
              (help-xref-button 1 'help-function-cmacro function lib)))))
      (insert ".\n"))))

(defun help-fns--signature (function doc real-def real-function buffer)
  "Insert usage at point and return docstring.  With highlighting."
  (if (keymapp function)
      doc                       ; If definition is a keymap, skip arglist note.
    (let* ((advertised (gethash real-def advertised-signature-table t))
           (arglist (if (listp advertised)
                        advertised (help-function-arglist real-def)))
           (usage (help-split-fundoc doc function)))
      (if usage (setq doc (cdr usage)))
      (let* ((use (cond
                   ((and usage (not (listp advertised))) (car usage))
                   ((listp arglist)
                    (help--make-usage-docstring function arglist))
                   ((stringp arglist) arglist)
                   ;; Maybe the arglist is in the docstring of a symbol
                   ;; this one is aliased to.
                   ((let ((fun real-function))
                      (while (and (symbolp fun)
                                  (setq fun (symbol-function fun))
                                  (not (setq usage (help-split-fundoc
                                                    (documentation fun)
                                                    function)))))
                      usage)
                    (car usage))
                   ((or (stringp real-def)
                        (vectorp real-def))
                    (format "\nMacro: %s"
                            (help--docstring-quote
                             (format-kbd-macro real-def))))
                   (t "[Missing arglist.  Please make a bug report.]")))
             ;; Insert "`X", not "(\` X)", when documenting `X.
             (use1 (replace-regexp-in-string
                    "\\`(\\\\=\\\\\\\\=` \\([^\n ]*\\))\\'"
                    "\\\\=`\\1" use t))
             (high (if buffer
                       (let (subst-use1 subst-doc)
                         (with-current-buffer buffer
                           (setq subst-use1 (substitute-command-keys use1))
                           (setq subst-doc (substitute-command-keys doc)))
                         (help-highlight-arguments subst-use1 subst-doc))
                     (cons use1 doc))))
        (let ((fill-begin (point))
              (high-usage (car high))
              (high-doc (cdr high)))
          (unless (and (symbolp function)
                       (get function 'reader-construct))
            (insert high-usage "\n"))
          (fill-region fill-begin (point))
          high-doc)))))

(defun help-fns--parent-mode (function)
  ;; If this is a derived mode, link to the parent.
  (let ((parent-mode (and (symbolp function)
                          (get function
                               'derived-mode-parent))))
    (when parent-mode
      (insert (substitute-command-keys "  Parent mode: `"))
      (let ((beg (point)))
        (insert (format "%s" parent-mode))
        (make-text-button beg (point)
                          'type 'help-function
                          'help-args (list parent-mode)))
      (insert (substitute-command-keys "'.\n")))))

(defun help-fns--obsolete (function)
  ;; Ignore lambda constructs, keyboard macros, etc.
  (let* ((obsolete (and (symbolp function)
			(get function 'byte-obsolete-info)))
         (use (car obsolete)))
    (when obsolete
      (insert "  This "
	      (if (eq (car-safe (symbol-function function)) 'macro)
		  "macro"
		"function")
	      " is obsolete")
      (when (nth 2 obsolete)
        (insert (format " since %s" (nth 2 obsolete))))
      (insert (cond ((stringp use) (concat ";\n  " use))
                    (use (format-message ";\n  use `%s' instead." use))
                    (t "."))
              "\n"))))

(add-hook 'help-fns-describe-function-functions
          #'help-fns--globalized-minor-mode)
(defun help-fns--globalized-minor-mode (function)
  (when (and (symbolp function)
             (get function 'globalized-minor-mode))
    (help-fns--customize-variable function " the global mode variable.")
    (terpri)))

;; We could use `symbol-file' but this is a wee bit more efficient.
(defun help-fns--autoloaded-p (function file)
  "Return non-nil if FUNCTION has previously been autoloaded.
FILE is the file where FUNCTION was probably defined."
  (let* ((file (file-name-sans-extension (file-truename file)))
	 (load-hist load-history)
	 (target (cons t function))
	 found)
    (while (and load-hist (not found))
      (and (stringp (caar load-hist))
	   (equal (file-name-sans-extension (caar load-hist)) file)
	   (setq found (member target (cdar load-hist))))
      (setq load-hist (cdr load-hist)))
    found))

(defun help-fns--interactive-only (function)
  "Insert some help blurb if FUNCTION should only be used interactively."
  ;; Ignore lambda constructs, keyboard macros, etc.
  (and (symbolp function)
       (not (eq (car-safe (symbol-function function)) 'macro))
       (let* ((interactive-only
               (or (get function 'interactive-only)
                   (if (boundp 'byte-compile-interactive-only-functions)
                       (memq function
                             byte-compile-interactive-only-functions)))))
         (when interactive-only
           (insert "  This function is for interactive use only"
                   ;; Cf byte-compile-form.
                   (cond ((stringp interactive-only)
                          (format ";\n  in Lisp code %s" interactive-only))
                         ((and (symbolp 'interactive-only)
                               (not (eq interactive-only t)))
                          (format-message ";\n  in Lisp code use `%s' instead."
                                          interactive-only))
                         (t "."))
                   "\n")))))

(add-hook 'help-fns-describe-function-functions #'help-fns--side-effects)
(defun help-fns--side-effects (function)
  (when (and (symbolp function)
             (or (function-get function 'pure)
                 (function-get function 'side-effect-free)))
    (insert "  This function does not change global state, "
            "including the match data.\n")))

(add-hook 'help-fns-describe-function-functions #'help-fns--disabled)
(defun help-fns--disabled (function)
  (when (and (symbolp function)
             (function-get function 'disabled))
    (insert "  This function is disabled.\n")))

(defun help-fns--first-release (symbol)
  "Return the likely first release that defined SYMBOL, or nil."
  ;; Code below relies on the etc/NEWS* files.
  ;; FIXME: Maybe we should also use the */ChangeLog* files when available.
  ;; FIXME: Maybe we should also look for announcements of the addition
  ;; of the *packages* in which the function is defined.
  (let* ((name (symbol-name symbol))
         (re (concat "\\_<" (regexp-quote name) "\\_>"))
         (news (directory-files data-directory t "\\`NEWS\\.[1-9]"))
         (place nil)
         (first nil))
    (with-temp-buffer
      (dolist (f news)
        (erase-buffer)
        (insert-file-contents f)
        (goto-char (point-min))
        (search-forward "\n*")
        (while (re-search-forward re nil t)
          (let ((pos (match-beginning 0)))
            (save-excursion
              ;; Almost all entries are of the form "* ... in Emacs NN.MM."
              ;; but there are also a few in the form "* Emacs NN.MM is a bug
              ;; fix release ...".
              (if (not (re-search-backward "^\\*.* Emacs \\([0-9.]+[0-9]\\)"
                                           nil t))
                  (message "Ref found in non-versioned section in %S"
                           (file-name-nondirectory f))
                (let ((version (match-string 1)))
                  (when (or (null first) (version< version first))
                    (setq place (list f pos))
                    (setq first version)))))))))
    (when first
      (make-text-button first nil 'type 'help-news 'help-args place))))

(add-hook 'help-fns-describe-function-functions
          #'help-fns--mention-first-release)
(add-hook 'help-fns-describe-variable-functions
          #'help-fns--mention-first-release)
(defun help-fns--mention-first-release (object)
  (let ((first (if (symbolp object) (help-fns--first-release object))))
    (when first
      (with-current-buffer standard-output
        (insert (format "  Probably introduced at or before Emacs version %s.\n"
                        first))))))

(defun help-fns-short-filename (filename)
  (let* ((abbrev (abbreviate-file-name filename))
         (short abbrev))
    (dolist (dir load-path)
      (let ((rel (file-relative-name filename dir)))
        (if (< (length rel) (length short))
            (setq short rel)))
      (let ((rel (file-relative-name abbrev dir)))
        (if (< (length rel) (length short))
            (setq short rel))))
    short))

(defun help-fns--analyze-function (function)
  ;; FIXME: Document/explain the differences between FUNCTION,
  ;; REAL-FUNCTION, DEF, and REAL-DEF.
  "Return information about FUNCTION.
Returns a list of the form (REAL-FUNCTION DEF ALIASED REAL-DEF)."
  (let* ((advised (and (symbolp function)
		       (advice--p (advice--symbol-function function))))
	 ;; If the function is advised, use the symbol that has the
	 ;; real definition, if that symbol is already set up.
	 (real-function
	  (or (and advised
                   (advice--cd*r (advice--symbol-function function)))
	      function))
	 ;; Get the real definition, if any.
	 (def (if (symbolp real-function)
                  (cond ((symbol-function real-function))
                        ((get real-function 'function-documentation)
                         nil)
                        (t (signal 'void-function (list real-function))))
		real-function))
	 (aliased (and def
                       (or (symbolp def)
                           ;; Advised & aliased function.
                           (and advised (symbolp real-function)
                                (not (eq 'autoload (car-safe def))))
                           (and (subrp def)
                                (not (string= (subr-name def)
                                              (symbol-name function)))))))
	 (real-def (cond
                    ((and aliased (not (subrp def)))
                     (let ((f real-function))
                       (while (and (fboundp f)
                                   (symbolp (symbol-function f)))
                         (setq f (symbol-function f)))
                       f))
		    ((subrp def) (intern (subr-name def)))
                    (t def))))
    (list real-function def aliased real-def)))

(defun help-fns-function-description-header (function)
  "Print a line describing FUNCTION to `standard-output'."
  (pcase-let* ((`(,_real-function ,def ,aliased ,real-def)
                (help-fns--analyze-function function))
               (file-name (find-lisp-object-file-name function (if aliased 'defun
                                                                 def)))
               (beg (if (and (or (byte-code-function-p def)
                                 (keymapp def)
                                 (memq (car-safe def) '(macro lambda closure)))
                             (stringp file-name)
                             (help-fns--autoloaded-p function file-name))
                        (concat
                         "an autoloaded " (if (commandp def)
                                              "interactive "))
                      (if (commandp def) "an interactive " "a "))))

    ;; Print what kind of function-like object FUNCTION is.
    (princ (cond ((or (stringp def) (vectorp def))
		  "a keyboard macro")
		 ((and (symbolp function)
                       (get function 'reader-construct))
                  "a reader construct")
		 ;; Aliases are Lisp functions, so we need to check
		 ;; aliases before functions.
		 (aliased
		  (format-message "an alias for `%s'" real-def))
		 ((subrp def)
		  (concat beg (if (eq 'unevalled (cdr (subr-arity def)))
		                  "special form"
                                "built-in function")))
		 ((autoloadp def)
		  (format "an autoloaded %s"
                          (cond
			   ((commandp def) "interactive Lisp function")
			   ((eq (nth 4 def) 'keymap) "keymap")
			   ((nth 4 def) "Lisp macro")
                           (t "Lisp function"))))
		 ((or (eq (car-safe def) 'macro)
		      ;; For advised macros, def is a lambda
		      ;; expression or a byte-code-function-p, so we
		      ;; need to check macros before functions.
		      (macrop function))
		  (concat beg "Lisp macro"))
		 ((byte-code-function-p def)
		  (concat beg "compiled Lisp function"))
                 ((module-function-p def)
                  (concat beg "module function"))
		 ((eq (car-safe def) 'lambda)
		  (concat beg "Lisp function"))
		 ((eq (car-safe def) 'closure)
		  (concat beg "Lisp closure"))
		 ((keymapp def)
		  (let ((is-full nil)
			(elts (cdr-safe def)))
		    (while elts
		      (if (char-table-p (car-safe elts))
			  (setq is-full t
				elts nil))
		      (setq elts (cdr-safe elts)))
		    (concat beg (if is-full "keymap" "sparse keymap"))))
		 (t "")))

    (if (and aliased (not (fboundp real-def)))
	(princ ",\nwhich is not defined.  Please make a bug report.")
      (with-current-buffer standard-output
	(save-excursion
	  (save-match-data
	    (when (re-search-backward (substitute-command-keys
                                       "alias for `\\([^`']+\\)'")
                                      nil t)
	      (help-xref-button 1 'help-function real-def)))))

      (when file-name
	;; We used to add .el to the file name,
	;; but that's completely wrong when the user used load-file.
	(princ (format-message " in `%s'"
                               (if (eq file-name 'C-source)
                                   "C source code"
                                 (help-fns-short-filename file-name))))
	;; Make a hyperlink to the library.
	(with-current-buffer standard-output
	  (save-excursion
	    (re-search-backward (substitute-command-keys "`\\([^`']+\\)'")
                                nil t)
	    (help-xref-button 1 'help-function-def function file-name))))
      (princ "."))))

(defun help-fns--ensure-empty-line ()
  (unless (eolp) (insert "\n"))
  (unless (eq ?\n (char-before (1- (point)))) (insert "\n")))

;;;###autoload
(defun describe-function-1 (function)
  (let ((pt1 (with-current-buffer (help-buffer) (point))))
    (help-fns-function-description-header function)
    (with-current-buffer (help-buffer)
      (fill-region-as-paragraph (save-excursion (goto-char pt1) (forward-line 0) (point))
                                (point))))
  (terpri)(terpri)

  (pcase-let* ((`(,real-function ,def ,_aliased ,real-def)
                (help-fns--analyze-function function))
               (doc-raw (condition-case nil
                            ;; FIXME: Maybe `documentation' should return nil
                            ;; for invalid functions i.s.o. signaling an error.
                            (documentation function t)
                          ;; E.g. an alias for a not yet defined function.
                          ((invalid-function void-function) nil)))
               (key-bindings-buffer (current-buffer)))

    ;; If the function is autoloaded, and its docstring has
    ;; key substitution constructs, load the library.
    (and (autoloadp real-def) doc-raw
         help-enable-autoload
         (string-match "\\([^\\]=\\|[^=]\\|\\`\\)\\\\[[{<]" doc-raw)
         (autoload-do-load real-def))

    (help-fns--key-bindings function)
    (with-current-buffer standard-output
      (let ((doc (condition-case nil
                     ;; FIXME: Maybe `help-fns--signature' should return `doc'
                     ;; for invalid functions i.s.o. signaling an error.
                     (help-fns--signature
                      function doc-raw
                      (if (subrp def) (indirect-function real-def) real-def)
                      real-function key-bindings-buffer)
                   ;; E.g. an alias for a not yet defined function.
                   ((invalid-function void-function) doc-raw))))
        (help-fns--ensure-empty-line)
        (run-hook-with-args 'help-fns-describe-function-functions function)
        (help-fns--ensure-empty-line)
        (insert (or doc "Not documented.")))
      ;; Avoid asking the user annoying questions if she decides
      ;; to save the help buffer, when her locale's codeset
      ;; isn't UTF-8.
      (unless (memq text-quoting-style '(straight grave))
        (set-buffer-file-coding-system 'utf-8)))))

;; Add defaults to `help-fns-describe-function-functions'.
(add-hook 'help-fns-describe-function-functions #'help-fns--obsolete)
(add-hook 'help-fns-describe-function-functions #'help-fns--interactive-only)
(add-hook 'help-fns-describe-function-functions #'help-fns--parent-mode)
(add-hook 'help-fns-describe-function-functions #'help-fns--compiler-macro)

\f
;; Variables

;;;###autoload
(defun variable-at-point (&optional any-symbol)
  "Return the bound variable symbol found at or before point.
Return 0 if there is no such symbol.
If ANY-SYMBOL is non-nil, don't insist the symbol be bound."
  (with-syntax-table emacs-lisp-mode-syntax-table
    (or (condition-case ()
	    (save-excursion
	      (skip-chars-forward "'")
	      (or (not (zerop (skip-syntax-backward "_w")))
		  (eq (char-syntax (following-char)) ?w)
		  (eq (char-syntax (following-char)) ?_)
		  (forward-sexp -1))
	      (skip-chars-forward "'")
	      (let ((obj (read (current-buffer))))
		(and (symbolp obj) (boundp obj) obj)))
          (error nil))
        (let* ((str (find-tag-default))
               (sym (if str (intern-soft str))))
          (if (and sym (or any-symbol (boundp sym)))
              sym
            (save-match-data
              (when (and str (string-match "\\`\\W*\\(.*?\\)\\W*\\'" str))
                (setq sym (intern-soft (match-string 1 str)))
                (and (or any-symbol (boundp sym)) sym)))))
        0)))

(defun describe-variable-custom-version-info (variable &optional type)
  (let ((custom-version (get variable 'custom-version))
	(cpv (get variable 'custom-package-version))
        (type (or type "variable"))
	(output nil))
    (if custom-version
	(setq output
	      (format "  This %s was introduced, or its default value was changed, in\n  version %s of Emacs.\n"
                      type custom-version))
      (when cpv
	(let* ((package (car-safe cpv))
	       (version (if (listp (cdr-safe cpv))
			    (car (cdr-safe cpv))
			  (cdr-safe cpv)))
	       (pkg-versions (assq package customize-package-emacs-version-alist))
	       (emacsv (cdr (assoc version pkg-versions))))
	  (if (and package version)
	      (setq output
		    (format (concat "  This %s was introduced, or its default value was changed, in\n  version %s of the %s package"
				    (if emacsv
					(format " that is part of Emacs %s" emacsv))
				    ".\n")
			    type version package))))))
    output))

;;;###autoload
(defun describe-variable (variable &optional buffer frame)
  "Display the full documentation of VARIABLE (a symbol).
Returns the documentation as a string, also.
If VARIABLE has a buffer-local value in BUFFER or FRAME
\(default to the current buffer and current frame),
it is displayed along with the global value."
  (interactive
   (let ((v (variable-at-point))
	 (enable-recursive-minibuffers t)
         (orig-buffer (current-buffer))
	 val)
     (setq val (completing-read
                (if (symbolp v)
                    (format
                     "Describe variable (default %s): " v)
                  "Describe variable: ")
                #'help--symbol-completion-table
                (lambda (vv)
                  ;; In case the variable only exists in the buffer
                  ;; the command we switch back to that buffer before
                  ;; we examine the variable.
                  (with-current-buffer orig-buffer
                    (or (get vv 'variable-documentation)
                        (and (boundp vv) (not (keywordp vv))))))
                t nil nil
                (if (symbolp v) (symbol-name v))))
     (list (if (equal val "")
	       v (intern val)))))
  (let (file-name)
    (unless (buffer-live-p buffer) (setq buffer (current-buffer)))
    (unless (frame-live-p frame) (setq frame (selected-frame)))
    (if (not (symbolp variable))
	(user-error "You didn't specify a variable")
      (save-excursion
	(let ((valvoid (not (with-current-buffer buffer (boundp variable))))
	      val val-start-pos locus)
	  ;; Extract the value before setting up the output buffer,
	  ;; in case `buffer' *is* the output buffer.
	  (unless valvoid
	    (with-selected-frame frame
	      (with-current-buffer buffer
		(setq val (symbol-value variable)
		      locus (variable-binding-locus variable)))))
	  (help-setup-xref (list #'describe-variable variable buffer)
			   (called-interactively-p 'interactive))
	  (with-help-window (help-buffer)
	    (with-current-buffer buffer
	      (prin1 variable)
	      (setq file-name (find-lisp-object-file-name variable 'defvar))

	      (princ (if file-name
		         (progn
		           (princ (format-message
                                   " is a variable defined in `%s'.\n"
                                   (if (eq file-name 'C-source)
                                       "C source code"
                                     (help-fns-short-filename file-name))))
		           (with-current-buffer standard-output
		             (save-excursion
			       (re-search-backward (substitute-command-keys
                                                    "`\\([^`']+\\)'")
                                                   nil t)
			       (help-xref-button 1 'help-variable-def
					         variable file-name)))
		           (if valvoid
			       "It is void as a variable."
                             "Its "))
                       (if valvoid
		           " is void as a variable."
                         (substitute-command-keys "'s ")))))
	    (unless valvoid
	      (with-current-buffer standard-output
		(setq val-start-pos (point))
		(princ "value is")
		(let ((line-beg (line-beginning-position))
		      (print-rep
		       (let ((rep
			      (let ((print-quoted t)
                                    (print-circle t))
				(cl-prin1-to-string val))))
			 (if (and (symbolp val) (not (booleanp val)))
			     (format-message "`%s'" rep)
			   rep))))
		  (if (< (+ (length print-rep) (point) (- line-beg)) 68)
		      (insert " " print-rep)
		    (terpri)
                    (let ((buf (current-buffer)))
                      (with-temp-buffer
                        (lisp-mode-variables nil)
                        (set-syntax-table emacs-lisp-mode-syntax-table)
                        (insert print-rep)
                        (pp-buffer)
                        (let ((pp-buffer (current-buffer)))
                          (with-current-buffer buf
                            (insert-buffer-substring pp-buffer)))))
                    ;; Remove trailing newline.
                    (and (= (char-before) ?\n) (delete-char -1)))
		  (let* ((sv (get variable 'standard-value))
			 (origval (and (consp sv)
				       (condition-case nil
					   (eval (car sv) t)
					 (error :help-eval-error))))
                         from)
		    (when (and (consp sv)
                               (not (equal origval val))
                               (not (equal origval :help-eval-error)))
		      (princ "\nOriginal value was \n")
		      (setq from (point))
		      (if (and (symbolp origval) (not (booleanp origval)))
			  (let* ((rep (cl-prin1-to-string origval))
				 (print-rep (format-message "`%s'" rep)))
			    (insert print-rep))
			(cl-prin1 origval))
                      (save-restriction
                        (narrow-to-region from (point))
                        (save-excursion (pp-buffer)))
		      (if (< (point) (+ from 20))
			  (delete-region (1- from) from)))))))
	    (terpri)
	    (when locus
	      (cond
               ((bufferp locus)
                (princ (format "Local in buffer %s; "
                               (buffer-name buffer))))
               ((terminal-live-p locus)
                (princ (format "It is a terminal-local variable; ")))
               (t
                (princ (format "It is local to %S" locus))))
	      (if (not (default-boundp variable))
		  (princ "globally void")
		(let ((global-val (default-value variable)))
		  (with-current-buffer standard-output
		    (princ "global value is ")
		    (if (eq val global-val)
			(princ "the same.")
		      (terpri)
		      ;; Fixme: pp can take an age if you happen to
		      ;; ask for a very large expression.  We should
		      ;; probably print it raw once and check it's a
		      ;; sensible size before prettyprinting.  -- fx
		      (let ((from (point)))
                        (cl-prin1 global-val)
                        (save-restriction
                          (narrow-to-region from (point))
                          (save-excursion (pp-buffer)))
			;; See previous comment for this function.
			;; (help-xref-on-pp from (point))
			(if (< (point) (+ from 20))
			    (delete-region (1- from) from)))))))
              (terpri))

	    ;; If the value is large, move it to the end.
	    (with-current-buffer standard-output
	      (when (> (count-lines (point-min) (point-max)) 10)
		;; Note that setting the syntax table like below
		;; makes forward-sexp move over a `'s' at the end
		;; of a symbol.
		(set-syntax-table emacs-lisp-mode-syntax-table)
		(goto-char val-start-pos)
		;; The line below previously read as
		;; (delete-region (point) (progn (end-of-line) (point)))
		;; which suppressed display of the buffer local value for
		;; large values.
		(when (looking-at "value is") (replace-match ""))
		(save-excursion
		  (insert "\n\nValue:")
		  (set (make-local-variable 'help-button-cache)
		       (point-marker)))
		(insert "value is shown ")
		(insert-button "below"
			       'action help-button-cache
			       'follow-link t
			       'help-echo "mouse-2, RET: show value")
		(insert ".\n")))
            (terpri)

            (let* ((alias (condition-case nil
                              (indirect-variable variable)
                            (error variable)))
                   (doc (or (documentation-property
                             variable 'variable-documentation)
                            (documentation-property
                             alias 'variable-documentation))))

              (with-current-buffer buffer
                (run-hook-with-args 'help-fns-describe-variable-functions
                                    variable))

              (with-current-buffer standard-output
                (help-fns--ensure-empty-line))
	      (princ "Documentation:\n")
	      (with-current-buffer standard-output
		(insert (or doc "Not documented as a variable."))))

	    (with-current-buffer standard-output
	      ;; Return the text we displayed.
	      (buffer-string))))))))

(add-hook 'help-fns-describe-variable-functions #'help-fns--customize-variable)
(defun help-fns--customize-variable (variable &optional text)
  ;; Make a link to customize if this variable can be customized.
  (when (custom-variable-p variable)
    (let ((customize-label "customize"))
      (princ (concat "  You can " customize-label (or text " this variable.")))
      (with-current-buffer standard-output
	(save-excursion
	  (re-search-backward
	   (concat "\\(" customize-label "\\)") nil t)
	  (help-xref-button 1 'help-customize-variable variable)))
      (terpri))
    ;; Note variable's version or package version.
    (let ((output (describe-variable-custom-version-info variable)))
      (when output
	;; (terpri)
	;; (terpri)
	(princ output)))))

(add-hook 'help-fns-describe-variable-functions #'help-fns--var-safe-local)
(defun help-fns--var-safe-local (variable)
  (let ((safe-var (get variable 'safe-local-variable)))
    (when safe-var
      (princ "  This variable is safe as a file local variable ")
      (princ "if its value\n  satisfies the predicate ")
      (princ (if (byte-code-function-p safe-var)
		 "which is a byte-compiled expression.\n"
	       (format-message "`%s'.\n" safe-var))))))

(add-hook 'help-fns-describe-variable-functions #'help-fns--var-risky)
(defun help-fns--var-risky (variable)
  ;; Can be both risky and safe, eg auto-fill-function.
  (when (risky-local-variable-p variable)
    (princ "  This variable may be risky if used as a \
file-local variable.\n")
    (when (assq variable safe-local-variable-values)
      (princ (substitute-command-keys
              "  However, you have added it to \
`safe-local-variable-values'.\n")))))

(add-hook 'help-fns-describe-variable-functions #'help-fns--var-ignored-local)
(defun help-fns--var-ignored-local (variable)
  (when (memq variable ignored-local-variables)
    (princ "  This variable is ignored as a file-local \
variable.\n")))

(add-hook 'help-fns-describe-variable-functions #'help-fns--var-file-local)
(defun help-fns--var-file-local (variable)
  (when (boundp variable)
    (let ((val (symbol-value variable)))
      (when (member (cons variable val)
                    file-local-variables-alist)
        (if (member (cons variable val)
                    dir-local-variables-alist)
	    (let ((file (and buffer-file-name
                             (not (file-remote-p buffer-file-name))
                             (dir-locals-find-file buffer-file-name)))
                  (is-directory nil))
	      (princ (substitute-command-keys
		      "  This variable's value is directory-local"))
              (when (consp file)       ; result from cache
                ;; If the cache element has an mtime, we
                ;; assume it came from a file.
                (if (nth 2 file)
                    ;; (car file) is a directory.
                    (setq file (dir-locals--all-files (car file)))
                  ;; Otherwise, assume it was set directly.
                  (setq file (car file)
                        is-directory t)))
              (if (null file)
                  (princ ".\n")
                (princ ", set ")
                (princ (substitute-command-keys
                        (cond
                         (is-directory "for the directory\n  `")
                         ;; Many files matched.
                         ((and (consp file) (cdr file))
                          (setq file (file-name-directory (car file)))
                          (format "by one of the\n  %s files in the directory\n  `"
                                  dir-locals-file))
                         (t (setq file (car file))
                            "by the file\n  `"))))
	        (with-current-buffer standard-output
	          (insert-text-button
	           file 'type 'help-dir-local-var-def
                   'help-args (list variable file)))
	        (princ (substitute-command-keys "'.\n"))))
          (princ (substitute-command-keys
	          "  This variable's value is file-local.\n")))))))

(add-hook 'help-fns-describe-variable-functions #'help-fns--var-watchpoints)
(defun help-fns--var-watchpoints (variable)
  (let ((watchpoints (get-variable-watchers variable)))
    (when watchpoints
      (princ "  Calls these functions when changed: ")
      ;; FIXME: Turn function names into hyperlinks.
      (princ watchpoints)
      (terpri))))

(add-hook 'help-fns-describe-variable-functions #'help-fns--var-obsolete)
(defun help-fns--var-obsolete (variable)
  (let* ((obsolete (get variable 'byte-obsolete-variable))
	 (use (car obsolete)))
    (when obsolete
      (princ "  This variable is obsolete")
      (if (nth 2 obsolete)
          (princ (format " since %s" (nth 2 obsolete))))
      (princ (cond ((stringp use) (concat ";\n  " use))
		   (use (format-message ";\n  use `%s' instead."
                                        (car obsolete)))
		   (t ".")))
      (terpri))))

(add-hook 'help-fns-describe-variable-functions #'help-fns--var-alias)
(defun help-fns--var-alias (variable)
  ;; Mention if it's an alias.
  (let ((alias (condition-case nil
                   (indirect-variable variable)
                 (error variable))))
    (unless (eq alias variable)
      (princ (format-message
              "  This variable is an alias for `%s'.\n"
              alias)))))

(add-hook 'help-fns-describe-variable-functions #'help-fns--var-aliases)
(defun help-fns--var-aliases (variable)
  ;; Mention if it has any aliases.
  (let (aliases alias)
    (mapatoms
     (lambda (sym)
       (when (and (boundp sym)
		  (setq alias (indirect-variable sym))
                  (eq alias variable)
		  (not (eq alias sym)))
	 (push sym aliases)))
     obarray)
    (when aliases
      (princ
       (if (= (length aliases) 1)
           (format-message
            "  This variable has an alias: `%s'.\n" (car aliases))
         (format-message
          "  This variable has the following aliases: %s.\n"
          (mapconcat
           (lambda (sym)
             (format "`%s'" sym))
           aliases ",\n    ")))))))

(add-hook 'help-fns-describe-variable-functions #'help-fns--var-bufferlocal)
(defun help-fns--var-bufferlocal (variable)
  (let ((permanent-local (get variable 'permanent-local))
        (locus (variable-binding-locus variable)))
    ;; Mention if it's a local variable.
    (cond
     ((and (local-variable-if-set-p variable)
	   (or (not (local-variable-p variable))
	       (with-temp-buffer
	         (local-variable-if-set-p variable))))
      (princ "  Automatically becomes ")
      (if permanent-local
	  (princ "permanently "))
      (princ "buffer-local when set.\n"))
     ((not permanent-local))
     ((bufferp locus)
      (princ
       (substitute-command-keys
        "  This variable's buffer-local value is permanent.\n")))
     (t
      (princ (substitute-command-keys
	      "  This variable's value is permanent \
if it is given a local binding.\n"))))))

\f
;; Faces.

;;;###autoload
(defun describe-face (face &optional frame)
  "Display the properties of face FACE on FRAME.
Interactively, FACE defaults to the faces of the character after point
and FRAME defaults to the selected frame.

If the optional argument FRAME is given, report on face FACE in that frame.
If FRAME is t, report on the defaults for face FACE (for new frames).
If FRAME is omitted or nil, use the selected frame."
  (interactive (list (read-face-name "Describe face"
                                     (or (face-at-point t) 'default)
                                     t)))
  (help-setup-xref (list #'describe-face face)
		   (called-interactively-p 'interactive))
  (unless face
    (setq face 'default))
  (if (not (listp face))
      (setq face (list face)))
  (with-help-window (help-buffer)
    (with-current-buffer standard-output
      (dolist (f face (buffer-string))
	(if (stringp f) (setq f (intern f)))
	;; We may get called for anonymous faces (i.e., faces
	;; expressed using prop-value plists).  Those can't be
	;; usefully customized, so ignore them.
	(when (symbolp f)
	  (insert "Face: " (symbol-name f))
	  (if (not (facep f))
	      (insert "   undefined face.\n")
	    (let ((customize-label "customize this face")
		  file-name)
	      (insert (concat " (" (propertize "sample" 'font-lock-face f) ")"))
	      (princ (concat " (" customize-label ")\n"))
	      ;; FIXME not sure how much of this belongs here, and
	      ;; how much in `face-documentation'.  The latter is
	      ;; not used much, but needs to return nil for
	      ;; undocumented faces.
	      (let ((alias (get f 'face-alias))
		    (face f)
		    obsolete)
		(when alias
		  (setq face alias)
		  (insert
		   (format-message
                    "\n  %s is an alias for the face `%s'.\n%s"
                    f alias
                    (if (setq obsolete (get f 'obsolete-face))
                        (format-message
                         "  This face is obsolete%s; use `%s' instead.\n"
                         (if (stringp obsolete)
                             (format " since %s" obsolete)
                           "")
                         alias)
                      ""))))
		(insert "\nDocumentation:\n"
                        (substitute-command-keys
                         (or (face-documentation face)
                             "Not documented as a face."))
			"\n\n"))
	      (with-current-buffer standard-output
		(save-excursion
		  (re-search-backward
		   (concat "\\(" customize-label "\\)") nil t)
		  (help-xref-button 1 'help-customize-face f)))
	      (setq file-name (find-lisp-object-file-name f 'defface))
	      (when file-name
		(princ (substitute-command-keys "Defined in `"))
		(princ (help-fns-short-filename file-name))
		(princ (substitute-command-keys "'"))
		;; Make a hyperlink to the library.
		(save-excursion
		  (re-search-backward
                   (substitute-command-keys "`\\([^`']+\\)'") nil t)
		  (help-xref-button 1 'help-face-def f file-name))
		(princ ".")
		(terpri)
		(terpri))))
	  (terpri)
          (run-hook-with-args 'help-fns-describe-face-functions f frame))))))

(add-hook 'help-fns-describe-face-functions
          #'help-fns--face-custom-version-info)
(defun help-fns--face-custom-version-info (face _frame)
  (when-let ((version-info (describe-variable-custom-version-info face 'face)))
    (insert version-info)
    (terpri)))

(add-hook 'help-fns-describe-face-functions #'help-fns--face-attributes)
(defun help-fns--face-attributes (face frame)
  (let* ((attrs '((:family . "Family")
		  (:foundry . "Foundry")
		  (:width . "Width")
		  (:height . "Height")
		  (:weight . "Weight")
		  (:slant . "Slant")
		  (:foreground . "Foreground")
		  (:distant-foreground . "DistantForeground")
		  (:background . "Background")
		  (:underline . "Underline")
		  (:overline . "Overline")
		  (:strike-through . "Strike-through")
		  (:box . "Box")
		  (:inverse-video . "Inverse")
		  (:stipple . "Stipple")
		  (:font . "Font")
		  (:fontset . "Fontset")
                  (:extend . "Extend")
		  (:inherit . "Inherit")))
	 (max-width (apply #'max (mapcar #'(lambda (x) (length (cdr x)))
					 attrs))))
    (dolist (a attrs)
      (let ((attr (face-attribute face (car a) frame)))
	(insert (make-string (- max-width (length (cdr a))) ?\s)
		(cdr a) ": " (format "%s" attr))
	(if (and (eq (car a) :inherit)
		 (not (eq attr 'unspecified)))
	    ;; Make a hyperlink to the parent face.
	    (save-excursion
	      (re-search-backward ": \\([^:]+\\)" nil t)
	      (help-xref-button 1 'help-face attr)))
	(insert "\n")))
    (terpri)))

(defvar help-xref-stack-item)

;;;###autoload
(defun describe-symbol (symbol &optional buffer frame)
  "Display the full documentation of SYMBOL.
Will show the info of SYMBOL as a function, variable, and/or face.
Optional arguments BUFFER and FRAME specify for which buffer and
frame to show the information about SYMBOL; they default to the
current buffer and the selected frame, respectively."
  (interactive
   (let* ((v-or-f (symbol-at-point))
          (found (if v-or-f (cl-some (lambda (x) (funcall (nth 1 x) v-or-f))
                                     describe-symbol-backends)))
          (v-or-f (if found v-or-f (function-called-at-point)))
          (found (or found v-or-f))
          (enable-recursive-minibuffers t)
          (val (completing-read (if found
				    (format
                                     "Describe symbol (default %s): " v-or-f)
				  "Describe symbol: ")
				#'help--symbol-completion-table
				(lambda (vv)
                                  (cl-some (lambda (x) (funcall (nth 1 x) vv))
                                           describe-symbol-backends))
				t nil nil
				(if found (symbol-name v-or-f)))))
     (list (if (equal val "")
	       (or v-or-f "") (intern val)))))
  (if (not (symbolp symbol))
      (user-error "You didn't specify a function or variable"))
  (unless (buffer-live-p buffer) (setq buffer (current-buffer)))
  (unless (frame-live-p frame) (setq frame (selected-frame)))
  (with-current-buffer (help-buffer)
    ;; Push the previous item on the stack before clobbering the output buffer.
    (help-setup-xref nil nil)
    (let* ((docs
            (nreverse
             (delq nil
                   (mapcar (pcase-lambda (`(,name ,testfn ,descfn))
                             (when (funcall testfn symbol)
                               ;; Don't record the current entry in the stack.
                               (setq help-xref-stack-item nil)
                               (cons name
                                     (funcall descfn symbol buffer frame))))
                           describe-symbol-backends))))
           (single (null (cdr docs))))
      (while (cdr docs)
        (goto-char (point-min))
        (let ((inhibit-read-only t)
              (name (caar docs))        ;Name of doc currently at BOB.
              (doc (cdr (cadr docs))))  ;Doc to add at BOB.
          (when doc
            (insert doc)
            (delete-region (point)
                           (progn (skip-chars-backward " \t\n") (point)))
            (insert "\n\n"
                    (eval-when-compile
                      (propertize "\n" 'face
                                  '(:height 0.1 :inverse-video t :extend t)))
                    "\n")
            (when name
              (insert (symbol-name symbol)
                      " is also a " name "." "\n\n"))))
        (setq docs (cdr docs)))
      (unless single
        ;; Don't record the `describe-variable' item in the stack.
        (setq help-xref-stack-item nil)
        (help-setup-xref (list #'describe-symbol symbol) nil))
      (goto-char (point-min)))))

;;;###autoload
(defun describe-syntax (&optional buffer)
  "Describe the syntax specifications in the syntax table of BUFFER.
The descriptions are inserted in a help buffer, which is then displayed.
BUFFER defaults to the current buffer."
  (interactive)
  (setq buffer (or buffer (current-buffer)))
  (help-setup-xref (list #'describe-syntax buffer)
		   (called-interactively-p 'interactive))
  (with-help-window (help-buffer)
    (let ((table (with-current-buffer buffer (syntax-table))))
      (with-current-buffer standard-output
	(describe-vector table 'internal-describe-syntax-value)
	(while (setq table (char-table-parent table))
	  (insert "\nThe parent syntax table is:")
	  (describe-vector table 'internal-describe-syntax-value))))))

(defun help-describe-category-set (value)
  (insert (cond
	   ((null value) "default")
	   ((char-table-p value) "deeper char-table ...")
	   (t (condition-case nil
		  (category-set-mnemonics value)
		(error "invalid"))))))

;;;###autoload
(defun describe-categories (&optional buffer)
  "Describe the category specifications in the current category table.
The descriptions are inserted in a buffer, which is then displayed.
If BUFFER is non-nil, then describe BUFFER's category table instead.
BUFFER should be a buffer or a buffer name."
  (interactive)
  (setq buffer (or buffer (current-buffer)))
  (help-setup-xref (list #'describe-categories buffer)
		   (called-interactively-p 'interactive))
  (with-help-window (help-buffer)
    (let* ((table (with-current-buffer buffer (category-table)))
	   (docs (char-table-extra-slot table 0)))
      (if (or (not (vectorp docs)) (/= (length docs) 95))
	  (error "Invalid first extra slot in this category table\n"))
      (with-current-buffer standard-output
        (setq-default help-button-cache (make-marker))
	(insert "Legend of category mnemonics ")
        (insert-button "(longer descriptions at the bottom)"
                       'action help-button-cache
                       'follow-link t
                       'help-echo "mouse-2, RET: show full legend")
        (insert "\n")
	(let ((pos (point)) (items 0) lines n)
	  (dotimes (i 95)
	    (if (aref docs i) (setq items (1+ items))))
	  (setq lines (1+ (/ (1- items) 4)))
	  (setq n 0)
	  (dotimes (i 95)
	    (let ((elt (aref docs i)))
	      (when elt
		(string-match ".*" elt)
		(setq elt (match-string 0 elt))
		(if (>= (length elt) 17)
		    (setq elt (concat (substring elt 0 14) "...")))
		(if (< (point) (point-max))
		    (move-to-column (* 20 (/ n lines)) t))
		(insert (+ i ?\s) ?: elt)
		(if (< (point) (point-max))
		    (forward-line 1)
		  (insert "\n"))
		(setq n (1+ n))
		(if (= (% n lines) 0)
		    (goto-char pos))))))
	(goto-char (point-max))
	(insert "\n"
		"character(s)\tcategory mnemonics\n"
		"------------\t------------------")
	(describe-vector table 'help-describe-category-set)
        (set-marker help-button-cache (point))
	(insert "Legend of category mnemonics:\n")
	(dotimes (i 95)
	  (let ((elt (aref docs i)))
	    (when elt
	      (if (string-match "\n" elt)
		  (setq elt (substring elt (match-end 0))))
	      (insert (+ i ?\s) ": " elt "\n"))))
	(while (setq table (char-table-parent table))
	  (insert "\nThe parent category table is:")
	  (describe-vector table 'help-describe-category-set))))))

(defun help-fns-find-keymap-name (keymap)
  "Find the name of the variable with value KEYMAP.
Return nil if KEYMAP is not a valid keymap, or if there is no
variable with value KEYMAP."
  (when (keymapp keymap)
    (let ((name (catch 'found-keymap
                  (mapatoms (lambda (symb)
                              (when (and (boundp symb)
                                         (eq (symbol-value symb) keymap)
                                         (not (eq symb 'keymap))
                                         (throw 'found-keymap symb)))))
                  nil)))
      ;; Follow aliasing.
      (or (ignore-errors (indirect-variable name)) name))))

(defun help-fns--most-relevant-active-keymap ()
  "Return the name of the most relevant active keymap.
The heuristic to determine which keymap is most likely to be
relevant to a user follows this order:

1. 'keymap' text property at point
2. 'local-map' text property at point
3. the `current-local-map'

This is used to set the default value for the interactive prompt
in `describe-keymap'.  See also `Searching the Active Keymaps'."
  (help-fns-find-keymap-name (or (get-char-property (point) 'keymap)
                         (if (get-text-property (point) 'local-map)
                             (get-char-property (point) 'local-map)
                           (current-local-map)))))

;;;###autoload
(defun describe-keymap (keymap)
  "Describe key bindings in KEYMAP.
When called interactively, prompt for a variable that has a
keymap value."
  (interactive
   (let* ((km (help-fns--most-relevant-active-keymap))
          (val (completing-read
                (format "Keymap (default %s): " km)
                obarray
                (lambda (m) (and (boundp m) (keymapp (symbol-value m))))
                t nil 'keymap-name-history
                (symbol-name km))))
     (unless (equal val "")
       (setq km (intern val)))
     (unless (and km (keymapp (symbol-value km)))
       (user-error "Not a keymap: %s" km))
     (list km)))
  (let (used-gentemp)
    (unless (and (symbolp keymap)
                 (boundp keymap)
                 (keymapp (symbol-value keymap)))
      (when (not (keymapp keymap))
        (if (symbolp keymap)
            (error "Not a keymap variable: %S" keymap)
          (error "Not a keymap")))
      (let ((sym nil))
        (unless sym
          (setq sym (cl-gentemp "KEYMAP OBJECT (no variable) "))
          (setq used-gentemp t)
          (set sym keymap))
        (setq keymap sym)))
    ;; Follow aliasing.
    (setq keymap (or (ignore-errors (indirect-variable keymap)) keymap))
    (help-setup-xref (list #'describe-keymap keymap)
                     (called-interactively-p 'interactive))
    (let* ((name (symbol-name keymap))
           (doc (documentation-property keymap 'variable-documentation))
           (file-name (find-lisp-object-file-name keymap 'defvar)))
      (with-help-window (help-buffer)
        (with-current-buffer standard-output
          (unless used-gentemp
            (princ (format-message "%S is a keymap variable" keymap))
            (if (not file-name)
                (princ ".\n\n")
              (princ (format-message
                      " defined in `%s'.\n\n"
                      (if (eq file-name 'C-source)
                          "C source code"
                        (help-fns-short-filename file-name))))
              (save-excursion
                (re-search-backward (substitute-command-keys
                                     "`\\([^`']+\\)'")
                                    nil t)
                (help-xref-button 1 'help-variable-def
                                  keymap file-name))))
          (when (and (not (equal "" doc)) doc)
            (princ "Documentation:\n")
            (princ (format-message "%s\n\n" doc)))
          ;; Use `insert' instead of `princ', so control chars (e.g. \377)
          ;; insert correctly.
          (insert (substitute-command-keys (concat "\\{" name "}"))))))
    ;; Cleanup.
    (when used-gentemp
      (makunbound keymap))))
\f
;;;###autoload
(defun describe-mode (&optional buffer)
  "Display documentation of current major mode and minor modes.
A brief summary of the minor modes comes first, followed by the
major mode description.  This is followed by detailed
descriptions of the minor modes, each on a separate page.

For this to work correctly for a minor mode, the mode's indicator
variable \(listed in `minor-mode-alist') must also be a function
whose documentation describes the minor mode.

If called from Lisp with a non-nil BUFFER argument, display
documentation for the major and minor modes of that buffer."
  (interactive "@")
  (unless buffer (setq buffer (current-buffer)))
  (help-setup-xref (list #'describe-mode buffer)
		   (called-interactively-p 'interactive))
  ;; For the sake of help-do-xref and help-xref-go-back,
  ;; don't switch buffers before calling `help-buffer'.
  (with-help-window (help-buffer)
    (with-current-buffer buffer
      (let (minor-modes)
	;; Older packages do not register in minor-mode-list but only in
	;; minor-mode-alist.
	(dolist (x minor-mode-alist)
	  (setq x (car x))
	  (unless (memq x minor-mode-list)
	    (push x minor-mode-list)))
	;; Find enabled minor mode we will want to mention.
	(dolist (mode minor-mode-list)
	  ;; Document a minor mode if it is listed in minor-mode-alist,
	  ;; non-nil, and has a function definition.
	  (let ((fmode (or (get mode :minor-mode-function) mode)))
	    (and (boundp mode) (symbol-value mode)
		 (fboundp fmode)
		 (let ((pretty-minor-mode
			(if (string-match "\\(\\(-minor\\)?-mode\\)?\\'"
					  (symbol-name fmode))
			    (capitalize
			     (substring (symbol-name fmode)
					0 (match-beginning 0)))
			  fmode)))
		   (push (list fmode pretty-minor-mode
			       (format-mode-line (assq mode minor-mode-alist)))
			 minor-modes)))))
	;; Narrowing is not a minor mode, but its indicator is part of
	;; mode-line-modes.
	(when (buffer-narrowed-p)
	  (push '(narrow-to-region "Narrow" " Narrow") minor-modes))
	(setq minor-modes
	      (sort minor-modes
		    (lambda (a b) (string-lessp (cadr a) (cadr b)))))
	(when minor-modes
	  (princ "Enabled minor modes:\n")
	  (make-local-variable 'help-button-cache)
	  (with-current-buffer standard-output
	    (dolist (mode minor-modes)
	      (let ((mode-function (nth 0 mode))
		    (pretty-minor-mode (nth 1 mode))
		    (indicator (nth 2 mode)))
		(save-excursion
		  (goto-char (point-max))
		  (princ "\n\f\n")
		  (push (point-marker) help-button-cache)
		  ;; Document the minor modes fully.
                  (insert-text-button
                   pretty-minor-mode 'type 'help-function
                   'help-args (list mode-function)
                   'button '(t))
		  (princ (format " minor mode (%s):\n"
				 (if (zerop (length indicator))
				     "no indicator"
				   (format "indicator%s"
					   indicator))))
		  (princ (help-split-fundoc (documentation mode-function)
                                            nil 'doc)))
		(insert-button pretty-minor-mode
			       'action (car help-button-cache)
			       'follow-link t
			       'help-echo "mouse-2, RET: show full information")
		(newline)))
	    (forward-line -1)
	    (fill-paragraph nil)
	    (forward-line 1))

	  (princ "\n(Information about these minor modes follows the major mode info.)\n\n"))
	;; Document the major mode.
	(let ((mode mode-name))
	  (with-current-buffer standard-output
            (let ((start (point)))
              (insert (format-mode-line mode nil nil buffer))
              (add-text-properties start (point) '(face bold)))))
	(princ " mode")
	(let* ((mode major-mode)
	       (file-name (find-lisp-object-file-name mode nil)))
	  (when file-name
	    (princ (format-message " defined in `%s'"
                                   (help-fns-short-filename file-name)))
	    ;; Make a hyperlink to the library.
	    (with-current-buffer standard-output
	      (save-excursion
		(re-search-backward (substitute-command-keys "`\\([^`']+\\)'")
                                    nil t)
		(help-xref-button 1 'help-function-def mode file-name)))))
	(princ ":\n")
	(princ (help-split-fundoc (documentation major-mode) nil 'doc)))))
  ;; For the sake of IELM and maybe others
  nil)
\f
;; Widgets.

(defvar describe-widget-functions
  '(button-describe widget-describe)
  "A list of functions for `describe-widget' to call.
Each function should take one argument, a buffer position, and return
non-nil if it described a widget at that position.")

;;;###autoload
(defun describe-widget (&optional pos)
  "Display a buffer with information about a widget.
You can use this command to describe buttons (e.g., the links in a *Help*
buffer), editable fields of the customization buffers, etc.

Interactively, click on a widget to describe it, or hit RET to describe the
widget at point.

When called from Lisp, POS may be a buffer position or a mouse position list.

Calls each function of the list `describe-widget-functions' in turn, until
one of them returns non-nil."
  (interactive
   (list
    (let ((key
           (read-key
            "Click on a widget, or hit RET to describe the widget at point")))
      (cond ((eq key ?\C-m) (point))
            ((and (mouse-event-p key)
                  (eq (event-basic-type key) 'mouse-1)
                  (equal (event-modifiers key) '(click)))
             (event-end key))
            ((eq key ?\C-g) (signal 'quit nil))
            (t (user-error "You didn't specify a widget"))))))
  (let (buf)
    ;; Allow describing a widget in a different window.
    (when (posnp pos)
      (setq buf (window-buffer (posn-window pos))
            pos (posn-point pos)))
    (with-current-buffer (or buf (current-buffer))
      (unless (cl-some (lambda (fun) (when (fboundp fun) (funcall fun pos)))
                       describe-widget-functions)
        (message "No widget found at that position")))))
\f

;;; Replacements for old lib-src/ programs.  Don't seem especially useful.

;; Replaces lib-src/digest-doc.c.
;;;###autoload
(defun doc-file-to-man (file)
  "Produce an nroff buffer containing the doc-strings from the DOC file."
  (interactive (list (read-file-name "Name of DOC file: " doc-directory
                                     internal-doc-file-name t)))
  (or (file-readable-p file)
      (error "Cannot read file `%s'" file))
  (pop-to-buffer (generate-new-buffer "*man-doc*"))
  (setq buffer-undo-list t)
  (insert ".TH \"Command Summary for GNU Emacs\"\n"
          ".AU Richard M. Stallman\n")
  (insert-file-contents file)
  (let (notfirst)
    (while (search-forward "\^_" nil 'move)
      (if (= (following-char) ?S)
          (delete-region (1- (point)) (line-end-position))
        (delete-char -1)
        (if notfirst
            (insert "\n.DE\n")
          (setq notfirst t))
        (insert "\n.SH ")
        (insert (if (= (following-char) ?F) "Function " "Variable "))
        (delete-char 1)
        (forward-line 1)
        (insert ".DS L\n"))))
  (insert "\n.DE\n")
  (setq buffer-undo-list nil)
  (nroff-mode))

;; Replaces lib-src/sorted-doc.c.
;;;###autoload
(defun doc-file-to-info (file)
  "Produce a texinfo buffer with sorted doc-strings from the DOC file."
  (interactive (list (read-file-name "Name of DOC file: " doc-directory
                                     internal-doc-file-name t)))
  (or (file-readable-p file)
      (error "Cannot read file `%s'" file))
  (let ((i 0) type name doc alist)
    (with-temp-buffer
      (insert-file-contents file)
      ;; The characters "@{}" need special treatment.
      (while (re-search-forward "[@{}]" nil t)
        (backward-char)
        (insert "@")
        (forward-char 1))
      (goto-char (point-min))
      (while (search-forward "\^_" nil t)
        (when (/= (following-char) ?S)
          (setq type (char-after)
                name (buffer-substring (1+ (point)) (line-end-position))
                doc (buffer-substring (line-beginning-position 2)
                                      (if (search-forward  "\^_" nil 'move)
                                          (1- (point))
                                        (point)))
                alist (cons (list name type doc) alist))
          (backward-char 1))))
    (pop-to-buffer (generate-new-buffer "*info-doc*"))
    (setq buffer-undo-list t)
    ;; Write the output header.
    (insert "\\input texinfo  @c -*-texinfo-*-\n"
            "@setfilename emacsdoc.info\n"
            "@settitle Command Summary for GNU Emacs\n"
            "@finalout\n"
            "\n@node Top\n"
            "@unnumbered Command Summary for GNU Emacs\n\n"
            "@table @asis\n\n"
            "@iftex\n"
            "@global@let@ITEM@item\n"
            "@def@item{@filbreak@vskip5pt@ITEM}\n"
            "@font@tensy cmsy10 scaled @magstephalf\n"
            "@font@teni cmmi10 scaled @magstephalf\n"
            "@def\\{{@tensy@char110}}\n" ; this backslash goes with cmr10
            "@def|{{@tensy@char106}}\n"
            "@def@{{{@tensy@char102}}\n"
            "@def@}{{@tensy@char103}}\n"
            "@def<{{@teni@char62}}\n"
            "@def>{{@teni@char60}}\n"
            "@chardef@@64\n"
            "@catcode43=12\n"
            "@tableindent-0.2in\n"
            "@end iftex\n")
    ;; Sort the array by name; within each name, by type (functions first).
    (setq alist (sort alist (lambda (e1 e2)
                              (if (string-equal (car e1) (car e2))
                                  (<= (cadr e1) (cadr e2))
                                (string-lessp (car e1) (car e2))))))
    ;; Print each function.
    (dolist (e alist)
      (insert "\n@item "
              (if (char-equal (cadr e) ?\F) "Function" "Variable")
              " @code{" (car e) "}\n@display\n"
              (nth 2 e)
              "\n@end display\n")
      ;; Try to avoid a save size overflow in the TeX output routine.
      (if (zerop (setq i (% (1+ i) 100)))
          (insert "\n@end table\n@table @asis\n")))
    (insert "@end table\n"
            "@bye\n")
    (setq buffer-undo-list nil)
    (texinfo-mode)))

(provide 'help-fns)

;;; help-fns.el ends here

debug log:

solving 617f6ae5e8 ...
found 617f6ae5e8 in https://git.savannah.gnu.org/cgit/emacs.git

(*) Git path names are given by the tree(s) the blob belongs to.
    Blobs themselves have no identifier aside from the hash of its contents.^

Code repositories for project(s) associated with this external index

	https://git.savannah.gnu.org/cgit/emacs.git
	https://git.savannah.gnu.org/cgit/emacs/org-mode.git

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.